Clearly there are definite observable differences in color after 5ppm. Why isn't there an extended OTO color comparison reference for FC levels above 5?
It wouldn't be that hard to make. I'm half tempted to start taking photos of the OTO vial anytime I get a whole number result (6.0, 7.0, etc..) with the FAS-DPD test.
It wouldn't be that hard to make. I'm half tempted to start taking photos of the OTO vial anytime I get a whole number result (6.0, 7.0, etc..) with the FAS-DPD test.